1. Field of the Invention
The present invention relates to an image recording medium, a sheet feeding device for the image recording medium, and an image forming apparatus that realizes print output of highly glossy photograph images according to execution of folding and heat-bonding of the image recording medium in a post-processing device after image formation.
2. Description of the Related Art
In recent years, as it is well known, technical attempts concerning various image forming apparatus have been carried out to obtain glossy images of a photographic image quality. In the present invention, a structure of an image forming apparatus that forms images of a photographic image quality on a recording medium including a transparent section and a non-transparent section is explained.
In the conventional technology disclosed in Japanese Patent Application Laid-Open No. 2000-321842, a sensor that detects reflected light from a recording medium is provided in a position on an upstream side in a recording medium conveying direction of registration rollers. A type of the recording medium is distinguished based on a result of the detection by the sensor.
On the other hand, in Japanese Patent Application Laid-Open No. 2005-10529, an image recording medium including a transparent section and a non-transparent section is disclosed.
In the conventional technology described in Japanese Patent Application Laid-Open No. 2000-321842, the sensor is provided in the position on the upstream side in the recording medium conveying direction of the registration rollers. Thus, when a difference in an amount of sag of the recording medium nipped between the registration rollers occurs or a leading edge of the recording medium shifts obliquely, it is difficult to accurately detect a boundary between the transparent section and the non-transparent section of the recording medium disclosed in Japanese Patent Application Laid-Open No. 2005-10529.
Various technical attempts described in (A) to (F) below have been carried out to obtain glossy images of a photographic image quality.
(A) As an example of an image forming apparatus, there is a color image forming apparatus including an intermediate transfer member onto which different color toner images of a plurality of colors are multiply transferred from at least one image bearing member, a transparent-toner developing unit that develops a transparent toner image, a second transfer unit that transfers the color toner images and the transparent toner image formed on the intermediate transfer member onto a transfer material, and a fixing unit that fixes the color toner images and the transparent toner image formed on the transfer material (see Japanese Patent Application Laid-Open No. 2002-341623). In the conventional example, high glossiness is obtained by, after usual image formation is carried out on a sheet, uniformly forming a transparent toner image over the sheet before the sheet is conveyed to the fixing unit and fixing the transparent toner image.
However, in this technology, for example, a heavy load is applied to the fixing unit because a transparent toner is always supplied to the entire surface of the sheet and there is a difference in toner thickness between an image section and a non-image section of the sheet.
(B) As an example of an image recording medium, there is a receiving sheet for electrophotography that has a toner receiving layer on one surface of a support member and a back layer on the other surface. The support member has a thermoplastic resin layer(s) on one surface or both surfaces of a base thereof. Binders in an uppermost layer on the toner receiving layer side and an uppermost layer on the back layer side are soap-free water-dispersed polymer having a glass transition temperature (Tg) of 20° C. to 80° C. At least one of the toner receiving layer and the back layer contains a polymeric antistatic agent (see Japanese Patent Application Laid-Open No. 2004-191678). In the receiving sheet, a special recording medium is used to make the receiving sheet glossy. Thermoplastic resin layers are provided in the front and the back of a sheet and, after normally fixing an image on the sheet, pressure and heat are further applied thereto to realize uniform glossiness on the surface thereof.
However, the effect of this technology is realized when the receiving sheet is used together with a special fixing device disclosed in Japanese Patent Application Laid-Open No. 2004-191678. Thus, there are problems in terms of a structure, cost, power consumption, and the like.
(C) As an example of a fixing unit, there are two fixing units, as a first fixing unit and a second fixing unit, provided in an image forming apparatus (see Japanese Patent Application Laid-Open No. 2003-270991). In this conventional technology, after usual fixing of a toner image (the first fixing unit), the fixing unit including a highly smooth belt melts a toner again and, then, cools and peels off the toner to obtain uniform glossiness making use of the smoothness of the belt.
However, as in (B) above, there are problems in terms of a structure, cost, power consumption, and the like.
(D) As an example of an image recording medium, there is an image display plate. In the image display plate, a transparent film and a print surface reversely printed on the rear surface of the transparent film are provided. A light back-reflection sheet is provided on the print surface of the transparent film. An adhesive surface is provided on a surface of the light back-reflection sheet corresponding to the print surface. The adhesive surface and the print surface are integrated (see Japanese Patent Application Laid-Open No. 2004-302044).
However, this technology is provided on condition that the light back-reflection sheet, on which it is difficult to print an image, is used. Since it is difficult to print an image on the light back-reflection sheet, the 0.5 transparent film is used to form the image display plate. It is not an object to the technology to pursue a photographic image quality.
(E) As an example of an image recording medium, an adhesive layer is formed on a transparent film and the transparent film is bonded to an image surface (a print surface) in the technology disclosed in Japanese Patent Application Laid-Open No. H10-278183.
However, since adhesiveness of an image and the transparent film is low, it is impossible to reproduce a photographic image quality.
(F) As an example of an image recording medium, an invention related to a heat sensitive adhesive that is heated to have adhesion is disclosed in Japanese Patent Application Laid-Open No. 2003-206455. However, the invention does not examine a technology for obtaining a photographic image having a simple structure and a satisfactory storage life. It is possible obtain a photographic image having a simple structure and a satisfactory storage life by bonding a recording medium having, in a part thereof, a transparent section and a non-transparent white medium including an adhesive layer and forming the recording medium and the non-transparent white medium as an integral recording medium.
However, since the recording medium formed has the adhesive layer, it is necessary to contrive a stocking method and a conveying method for the recording medium. Moreover, in bonding the medium and the recording medium, since a bonding position is determined at a point when an adhesive surface of the medium comes into contact with the recording medium, it is necessary to contrive positioning of the medium before bonding.
As described above, in all the conventional technologies (A) to (F), structures of image forming apparatuses are complicated and there are problems in terms of cost, power consumption, a storage life of an image, and the like.